Starter quiz
- Match the pairs of number complements to 100
- 16⇔84 ✓
- 55⇔45 ✓
- 31⇔69 ✓
- 42⇔58 ✓
- Use a mental strategy to sum these multiples of 10 560 + 120 = ______
- '680' ✓
- Add together these multiples of 1,000 using a mental strategy. {{ ]} = 15,000 + 27,000
- '42,000' ✓
- Complete this subtraction using a mental strategy. 67,000 − 12,000 = ______
- '55,000' ✓
- How much change would I get from £20 if I spent £11.75 on a new football? £______ change.
- '8.25' ✓
- I have a ball of old plasticine that weighs 750 g and a new jumbo pack that weight 1.2 kg. What mass of plasticine do I have altogether?
- '1.95 kg' ✓
Exit quiz
- Which of the following expressions is not equivalent to the others?
- 57 − 51
- 56 − 50
- 55 − 45 ✓
- 54 − 48
- 53 − 47
-
- Which of the following expressions is not equivalent to the others?
- 248 − 203
- 249 − 204
- 250 − 205
- 250 − 206 ✓
- 252 − 207
-
- Match the expression with the adjustment to the minuend and subtrahend that will make them more efficient for calculation.
- 81 − 24⇔− 1 ✓
- 69 − 43⇔+ 1 ✓
- 52 − 37⇔− 2 ✓
- 65 − 47⇔+ 3 ✓
- Use adjustment of the minuend and subtrahend followed by your understanding of place value. 20.58 − 5.96 = ______
- '14.62' ✓
- Use adjustment of the minuend and subtrahend followed by partitioning to calculate the following subtraction. 70,559 − 54,504 = ______
- '16,055' ✓
- Use adjustment followed by a written procedure to calculate the following. 40,000 − 2,654 = ______
- '37,346' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- It is easier to use a written strategy for subtraction when no exchanging is required.
- If the minuend and subtrahend are both increased by the same amount, the difference stays the same.
- If the minuend and subtrahend are both decreased by the same amount, the difference stays the same.
Common misconception
Pupils may struggle to understand the purpose of transforming calculations using constant difference, especially if they are less confident in calculating using mental strategies.
Show pupils sequences of calculations with a constant difference and get them to spot which of them is easiest to complete. Start as simply as you need to here. Constant difference is a helpful tool not a new method designed to lower confidence.
Keywords
Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another.
Difference - The difference is the result after subtracting one number from another.
Constant - A constant is a quantity that has a fixed value that does not change or vary, such as a number.
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